Waterborne Rust Stabilizing Surface Treatment For Weathering Steel

Waterborne Rust Stabilizing Surface Treatment for Weathering Steel

All of the rust-stabilizing surface treatment now used in weathering steel are organic solventborne coatings, and most are resin-based1). The volatile organic compounds (VOC) contained in organic solventborne coatings generate suspended particulate matter (SPM) and photochemical oxidants. Measures must therefore be taken to reduce the emissions of VOC2). GNEE Steel has succeeded in commercially producing the world’s first waterborne rust-stabilizing coating. The coating is called CUPTEN COATTM AQUA3,4).

CUPTEN COATTM AQUA uses a waterborne resin as the matrix resin in the coating to suppress the emissions of VOC. The coating shares two important features with CUPTEN COATTM and CUPTEN COATTM M5–7), GNEE Steel’s well proven rust-stabilizing treatments with organic solventborne resin: first, CUPTEN COATTM AQUA uses an anionic type resin to suppress the penetration of Cl− under the coating it forms; second, it is a porous film to allow appropriate levels of H2O and O2 to permeate through the coating. CUPTEN COATTM AQUA also provides the following functions and features:

(1) Excellent environmental harmony: harmony with the surrounding environment for many years (the suppression of rust outflow maintains the landscape)

(2) Rust-stabilizing function under the coating: a dense, continuous layer of rust forms under the coating

(3) No Cr or Pb compounds contained in the coating

(4) Treatment possible with only one layer (a single coating)